Gabriele Cosmo
204 lines
8.4 KiB
Plaintext
204 lines
8.4 KiB
Plaintext
$Id: README 107435 2017-11-13 07:34:58Z gcosmo $
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-----------------------------------------------------
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=========================================================
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Geant4 - an Object-Oriented Toolkit for Simulation in HEP
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=========================================================
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TestEm5
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-------
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How to study the transmission, absorption and reflection of particles through
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a single, thin or thick, layer of material.
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In particular, the effects of the multiple scattering can be plotted.
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1- GEOMETRY DEFINITION
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The "absorber" is a box made of a given material.
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Three parameters define the absorber :
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- the material of the absorber,
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- the thickness of an absorber,
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- the transverse size of the absorber (the input face is a square).
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A volume "World" contains the "absorber".
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In addition a transverse uniform magnetic field can be applied.
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The default geometry is constructed in DetectorConstruction class, but all the
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parameters can be changed via commands defined in the DetectorMessenger class.
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The parameters of the "World" can be changed, too. However, if World material
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is not set to vacuum, the plots 10->43 below may be not pertinent.
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2- PHYSICS LIST
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Physics lists are based on modular design. Several modules are instantiated:
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1. Transportation
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2. EM physics
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3. Decays
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4. StepMax - for step limitation
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EM physics builders can be local (eg. in this example) or from G4 kernel
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physics_lists subdirectory.
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Local physics builders:
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- "local" standard EM physics with current 'best' options setting
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these options are explicited in PhysListEmStandard
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- "standardSSM" standard EM physics with alternative single Coulomb
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scattering model instead of multiple scattering.
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From geant4/source/physics_lists/builders:
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- "emstandard_opt0" recommended standard EM physics for LHC
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- "emstandard_opt1" best CPU performance standard physics for LHC
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- "emstandard_opt2" similar fast simulation
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- "emstandard_opt3" best standard EM options - analog to "local" above
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- "emstandard_opt4" best current advanced EM options standard + lowenergy
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- "emstandardWVI" standard EM physics and WentzelVI multiple scattering
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- "emstandardSS" standard EM physics and single scattering model
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- "emlivermore" low-energy EM physics using Livermore data
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- "empenelope" low-energy EM physics implementing Penelope models
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- "emlowenergy" low-energy EM physics implementing experimental
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low-energy models
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Physics lists and options can be (re)set with UI commands
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Please, notice that options set through G4EmProcessOptions are global, eg
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for all particle types. In G4 builders, it is shown how to set options per
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particle type.
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3- AN EVENT : THE PRIMARY GENERATOR
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The primary kinematic consists of a single particle which hits the absorber
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perpendicular to the input face. The type of the particle and its energy are
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set in the PrimaryGeneratorAction class, and can be changed via the G4
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build-in commands of G4ParticleGun class (see the macros provided with this
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example).
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In addition one can choose randomly the impact point of the incident particle.
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The interactive command is built in PrimaryGeneratorMessenger class.
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4- VISUALIZATION
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The Visualization Manager is set in the main().
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The initialisation of the drawing is done via the commands in vis.mac
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In interactive session:
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PreInit or Idle > /control/execute vis.mac
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The example has a default view which is a longitudinal view of the detector.
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The tracks are drawn at the end of event, and erased at the end of run.
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Optionally one can choose to draw all particles, only the charged, or none.
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This command is defined in EventActionMessenger class.
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5- TRACKING
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During the tracking, one can keep or not the secondaries : see StackingAction
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class and its Messenger (StackingMessenger).
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One can also limit 'by hand' the step lenght of the particle. As an example,
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this limitation is implemented as a 'full' process : see StepMax class and its
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Messenger. The 'StepMax process' is registered in the Physics List.
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6- DETECTOR RESPONSE
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At the end of a run, from the histogram(s), one can study different
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physics quantities such as :
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- energy deposit in the absorber,
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- energy spectrum of secondaries at creation,
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- energy spectrum and angle distribution of particles at exit,
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- transmission and backscattering coefficients,
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- ...
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7- List of the built-in histograms
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----------------------------------
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The test contains more than 60 built-in 1D histograms, which are managed by
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G4AnalysisManager class and its Messenger. The histos can be individually activated
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with the command :
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/analysis/h1/set id nbBins valMin valMax unit
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where unit is the desired unit for the histo (MeV or keV, deg or mrad, etc..)
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(see the macros xxxx.mac).
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1 "energy deposit in absorber"
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2 "energy of charged secondaries at creation"
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3 "energy of neutral secondaries at creation"
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4 "energy of charged at creation (log10(Ekin))"
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5 "energy of neutral at creation (log10(Ekin))"
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6 "x_vertex of charged secondaries (all)"
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7 "x_vertex of charged secondaries (not absorbed)"
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10 "(transmit, charged) : kinetic energy at exit of world"
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11 "(transmit, charged) : ener fluence: dE(MeV)/dOmega"
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12 "(transmit, charged) : space angle dN/dOmega"
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13 "(transmit, charged) : projected angle at exit of world"
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14 "(transmit, charged) : projected position at exit of world"
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15 "(transmit, charged) : radius at exit of world"
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20 "(transmit, neutral) : kinetic energy at exit of world"
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21 "(transmit, neutral) : ener fluence: dE(MeV)/dOmega"
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22 "(transmit, neutral) : space angle dN/dOmega"
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23 "(transmit, neutral) : projected angle at exit of world"
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30 "(reflect , charged) : kinetic energy at exit of world"
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31 "(reflect , charged) : ener fluence: dE(MeV)/dOmega"
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32 "(reflect , charged) : space angle dN/dOmega"
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33 "(reflect , charged) : projected angle at exit of world"
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40 "(reflect , neutral) : kinetic energy at exit of world"
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41 "(reflect , neutral) : ener fluence: dE(MeV)/dOmega"
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42 "(reflect , neutral) : space angle dN/dOmega"
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43 "(reflect , neutral) : projected angle at exit of world"
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50 "energy of Auger e- at creation"
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51 "energy of fluorescence gamma at creation"
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52 "energy of Auger e- at creation (log scale)"
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53 "energy of fluorescence gamma at creation (log scale)"
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54 "energy of PIXE Auger e- at creation"
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55 "energy of PIXE gamma at creation"
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56 "energy of PIXE Auger e- at creation (log scale)"
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57 "energy of PIXE gamma at creation (log scale)"
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58 "energy of G4DNA Auger e- at creation"
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59 "energy of G4DNA gamma at creation"
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60 "energy of G4DNA Auger e- at creation (log scale)"
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61 "energy of G4DNA gamma at creation (log scale)"
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The histograms can be viewed using ROOT or PAW.
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One can control the name of the histograms file with the command:
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/analysis/setFileName name (default testem5)
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It is possible to choose the format of the histogram file : root (default),
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hbook, xml, csv, by using namespace in HistoManager.hh
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It is also possible to print selected histograms on an ascii file:
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/analysis/h1/setAscii id
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All selected histos will be written on a file name.ascii (default testem5)
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8- GEANT4/GEANT3/DATA COMPARISON
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A Geant4/Geant3/exp. data comparison is given here for a few cases.
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These cases can be classified as follow:
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- e-/e+ incident particles versus protons and others.
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- 3 energy regimes: low: < 1MeV; medium: 1MeV -> few 10MeV; high: > 100MeV
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We indicate here the corresponding macros.
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| low energy | medium energy | high energy
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--------------------------------------------------------
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| acosta.mac | |
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e-+ | berger.mac | hanson.mac |
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| hunger.mac | kulchi.mac |
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| tavola.mac | |
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--------------------------------------------------------
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others| bichsel.mac | vincour.mac | shen1.mac shen2.mac
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| | gottsch.mac | tramu.mac
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--------------------------------------------------------
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The relevant part of the GEANT3 code is in the subdirectory geant3 together
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with the xxxx.dat input files.
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9- HOW TO START ?
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- execute TestEm5 in 'batch' mode from macro files e.g.
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% $(G4INSTALL)/bin/$(G4SYSTEM)/TestEm5 myMacro.mac
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- execute TestEm5 in 'interactive' mode with visualization e.g.
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% $(G4INSTALL)/bin/$(G4SYSTEM)/TestEm5
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Then type your commands, for instance :
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Idle> control/execute vis.mac
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Idle> run/beamOn 5
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....
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